Electric drive unit

摘要

An electric drive unit includes an electric motor, an inverter supplying electricity to the motor, a continuous current stage supplying electricity to the inverter, a controller including a modulator for driving the inverter controlled by a first digital signal representing the amplitude of the phase voltages to be applied to the motor and by a second digital signal representing the electrical frequency of the phase voltages. An analog/digital stage calculates the optimum value of the advance angle (δopt) of the voltage applied to the motor relative to the counter-electromotive force (“CEMF”) as a linear function of the peak value of the phase current and an analog/digital stage for measuring the angle (φact) between the voltage applied to the electric motor and the phase current. The controller is programmed for estimating the angle (γact) between the phase current and the CEMF as the difference between δopt and φact.

主权项

1. An electric drive unit comprising:
an electric motor with permanent magnets, an inverter supplying the electric motor, a continuous current stage supplying the inverter, a modulator driving the inverter, a controller controlling the modulator by a first digital signal (Vs_act) representing an amplitude of phase voltages (Vs) to be applied to the electric motor and by a second digital signal (freq_act) representing an electrical frequency of the phase voltages to be applied to the electric motor based on a reference frequency (freq_set) set outside or inside the controller; a first analogue/digital stage for calculating an optimum value of an advance angle (δopt) of the voltage (Vs) applied to the electric motor relative to a counter-electromotive force (Es), a second analogue/digital stage for measuring an angle (φact) between the voltage (Vs) applied to the electric motor and a phase current (Is), a temperature sensor positioned close to the permanent magnets and in communication with the first analogue/digital stage for providing to the first analogue/digital stage information relating to a temperature of the permanent magnets, the first analogue/digital stage being designed for calculating the optimum value of the advance angle (δopt) as a linear function of a peak value of the phase current (Is) according to a following equation:δopt=π·Ls·pKcorr·60·KE⁢⁢0·[1+αmag·(Tmag-T0⁢mag)]·Is where “Ls” is a synchronous inductance of the electric motor expressed in Henry, “p” is a number of poles of the electric motor, “Kcorr” is a corrective coefficient with a value greater than 1 and less than 1.2, “KE0” is a counter-electromotive force constant at a reference temperature “T0mag” of the permanent magnets, “αmag” is a coefficient of variation with a residual induction temperature of the permanent magnets, “Tmag” is the temperature of the permanent magnets measured by the temperature sensor, the controller being programmed for estimating, with an electrical frequency sampling, an angle γact between the phase current (Is) and the counter-electromotive force (Es) as a difference between the optimum value of the advance angle (δopt) and the angle (φact) measured between the voltage (Vs) applied to the electric motor and the phase current (Is).